Device for delivering a measured charge of a flowable powder

ABSTRACT

A device for delivering a measured charge of a flowable powder comprising a storage container, a vertical piston rod and a buffer vessel, the rod being provided with a constriction which reaches into the storage container when the piston rod is at the upper end of its stroke, and reaches into the buffer vessel when the piston rod is at the lower end of its stroke. In the latter position the piston rod fits tightly in a first channel which is in connection with a second channel which has a clearing rod. At one end of its stroke the clearing rod occupies the second channel and at the opposite end of its stroke establishes a communication between the first channel and the open end of the second channel.

United States Patent [1 1 Ebner et al. Aug. 7, 1973 [54] DEVICE FOR DELIVERING A MEASURED 3,233,790 2/1966 Shichizaemon MOgi 222/254 CHARGE OF A FLOWABLE POWDER 2,847,147 8/1958 Land ZZZ/365 X 2 3,248,] 18 4/1966 Pechy 277/l [75 Inventors: Helmut Ebner; Bernd Stumer; Hans Lang, all of Frankfurt/Mam, Primary Examiner-Robert B. Reeves Germany Assistant Examiner-Thomas E. Kocovsky [73] Assignee: Farbwerke Hoechst Aktiengeselly Koster schaft Vormals Meister Lucius 8: Bruning, Frankfurt am Main, Germany [57] ABSTRACT [22] Filed; Dec. 16, 1971 A device for delivering a measured charge of a flowable powder comprising a storage container, a vertical pis- [21 1 Appl' 208839 ton rod and a buffer vessel, the rod being provided with a constriction which reaches into the storage container [30] Foreign Application Priority Data when the piston rod is at the upper end of its stroke, Dec. 18 1970 Gerinany P 20 62 513.2 and reaches thebuffef vessel whenrthe Piston rod t y is at the lower end of its stroke. In the latterfposition the [52] 222/254 23/252 R 23/288 E, piston rod fits tightly in a first channel which is in con- 23/289, 222/365, 277/59 nection with a second channel which has a clearing rod. 51 Int. Cl B01j 4/02 At one end of its Stroke h clearing rod occupiesihe 58 Field of Search 23/288 R, 288 E, Second channel and at the Opposite end of its Stroke 23/252 R, 2 9; 277 59; 252 254 2 5 tablishes a Communication between the first channel 3 5 453 47 ;-214 17 A 17 C 7 AC and the open'end Of the second channel.

[56] References Cited 6 Claims, 2 Drawing Figures UNITED STATES PATENTS 2,358,956 9/1944 Ashbaugh 222/252 X 2,649,289 8/1953 Giberson .....-....,.....222/254x DEVICE FOR DELIVERING A MEASURED CHARGE OF A FLOWABLE POWDER The present invention relates to a device for delivering a measured unit volume or charge of a flowable powder, especially into a gas space under superatmospheric pressure. More particularly, the present invention relates to the charging of powdery catalysts and powdery reaction components into the gas space of a reactor operated under relatively high pressure.

The devices proposed for charging unit volumes of powdery solids generally comprise a storage container and a feeding device. In most cases, the storage container is an open vessel, and worms, disks or rolls with cells are used as the feeding device. The charge of powder is determined directly by the feeding device or a measuring vessel connected thereafter. In some known devices, for example, balances with a turning container for measuring sticky solids by weight, mechanical discharging devices are used for cleaning the cylindrical measuring vessel.

Most of the known devices can be constructed with appropriate casings so as to be dust-proof. It is difficult, however, to introduce powders against superatmospheric pressures with encased devices as even small increases above atmospheric pressure cause the gas to pass back through the feeding and measuring means whereby the charging of flowable powders, which is at best inaccurate, is rendered more difficult. The known devices fail completely if they are operated against high gas pressures, for example, in the range of from to 50 atmospheres gauge.

It is an object of the present invention to do away with the aforesaid drawback and to provide a device for delivering measured charges of flowable powders into a gas space in which the back pressure of gas into the feeding device and storage container are reliably avoided.

The present invention provides a device for delivering a measured charge of a flowable powder, comprising a vertical, slidably mounted piston rod, which rod passes through a storage container and tits tightly in a passage connecting the storage container with a lower, buffer vessel, the rod being provided with a constriction, which constriction reaches into the storage container when, and only when, the piston rod is at the upper end of its stroke, and reaches into the buffer vessel when, and only when, the piston rod is at the lower end of its stroke, the portion of the piston rod below the constriction fitting tightly in a first channel, which is in connection with a second channel which has aclearing' rod slidably mounted and fitting tightly therein, the second channel being open at one end, the clearing rod occupying thesecond channel at one end ofits stroke and at'the opposite end of its stroke enabling a communication to be established between the first channel and the open end of the second channel.

The invention will now be described by way of example with reference to the accompanying drawing in which:

FIG. I is a longitudinal view of a device according to the invention and FIG. 2 is a part-sectional view of the device shown in FIG. 1.

The vertical piston rod 2 is provided with a constriction 1 to measure and carry the charge of the material to be introduced. In FIG. 1, the piston rod 2 is in its lower end position where the constriction 1 projects into a buffer vessel 4.'At the upper end position of the piston, the constriction 1 is situated in a storagecontainer 3. The end of the piston rod 2 below the constric tion 1 is fitted tightly in a channel 5. Part of the said channel is visible in FIG. 2. In FIG. 1, the lower end of the channel 5 is hidden behind the lower end of the piston rod 2. The channel 5 is in connection with a channel 6 of a clearing rod 7 as can be seen in FIG. 2. At one end of its stroke, the clearing rod 7 occupies the channel 6 as shown in FIG. 1, while at the other end of the stroke of the clearing rod 7, the channel 6 is open to the gas space of the reactor via a connection 8, the mouth of the channel 5 is in connection with the channel 6, and a connection 9 to a blowing device not shown is open. The blowing device comprises a pressure gas container or a tube net in communication with the connection 9 by way of a valve 15.

The pistons can be driven in known manner by a gear and programming disk or advantageously by pneumatic means. In FIG. 1 are shown pneumatic cylinders 10 and 11, which are in communication via three-way valves with a known pressure gas source not shown. The' valves can be opened and closed in known manner by electric devices, for example, a programme switch. The

term known" is used herein to mean in actual use or described in the literature of the art.

To improve the sealing, stuffing boxes 12 with suction channels following them are advantageously installed in the channels 5 and 6. This is of special advantage when the powder to be charged is a catalyst used to initiate or accelerate a reaction in the gas space of a connected reactor. In this case, even very small amounts of gas penetrating into the buffer vessel 4 owing to leaky pistons or stuffing boxes could result in a breakdown of the device. In the device according to the invention, gaseous reactants are prevented in simple manner from penetrating into the buffer vessel 4 and the storage container 3 by means of a suction channel 13 which is connected with a vacuum installation of known type by way of a valve 17. Depending on the position of valves 15 and 18, the connection 9 in the guide channel 6 may also act as a suction channel.

The invention is now further described with reference to the position of the piston rod 2 and the clearing rod 7 as represented in FIG. I. In this phase, the valve 18 is open while valves 15 and 17 are closed. The buffer vessel 4 contains a powdery catalyst in an amount corresponding to the volume of constriction I in piston rod 2. Storage container 3 is at least partially charged with the powdery catalyst: under a blanket of nitrogen introduced through conduit 19.

The operational cycles of the device according to the invention are as follows:

Piston rod 2 is moved, to the upper end position which is reached when constriction 1 projects into storage container 3 to such an extent that it is filled with powder. In this position, the powder contained in buffer vessel 4 is discharged into channel 5 of piston rod 2. Then the piston rod 2 is moved downwards to .an intermediate position as represented in FIG. Zso that the powder in channel 5 is not compressed. The powder now contained in the contriction 1 cannot yet fall into the buffer vessel 4.

In the rest of the cycle, valves I5 and 17 are opened, the valve 18 is closed and the clearing rod 7 isreturned to the position represented in FIG. 2. Under a pressure which is some atmospheres greater than the pressure in the gas space of the reactor, a gaseous reactant or a gas which is inert in the reaction flows through the open valve 15 into the free space of channels 5 and 6 and blows the powder contained therein through a connection 8 into the gas space. The piston rod 2 and the clearing rod 7 return to their initial position one after the other and push any residues of the powder which may still be present out of the channels. Next, the valve is closed and the valve 18 is opened.

The starting position is now reached again. The operational cycle of the rods and valves is repeated either immediately or after a definite period of time. From the above description it can be seen that the clearing rod 7 not only functions as cleaner but also serves as locking element.

If a reaction of the powder or an initiation of a reaction by the powder are not to be feared, the suctioning means behind the stuffing boxes may be dispensed with.

What is claimed is:

l. A device for delivering a measured charge of a flowable powder, said device comprising a storage container for said powder and a buffer vessel located downstream of said storage container andin communication therewith through a flow passage in said device, means defining first and-second flow conduits in said device with said first conduit being located in communication with said buffer vessel and in axial alignment with said flow passage, said second conduit being located at an angle with respect to said first conduit, in communication therewith, and having an open discharge end; a first elongated rod slidably mounted in said flow passage for reciprocating movement therein and having one end thereof slidably received in said first conduit, said first elongated rod having a constriction formed therein intermediate its ends, and means for reciprocating said first elongated rod between first and second positions wherein, at said first position said constriction is located in said storage container to receive said measured charge of powder and said one end of the rod is located in said buffer vessel, and at said second position said constriction is located in said buffer vessel to deposit said measured powder charge therein and said one end of the rod is located in said first conduit; a second elongated rod slidably received in said second conduit, and means for reciprocating said second rod independently of said first rod between a first retracted position wherein said second conduit is opened to provide communication between the open end thereof and said first conduit and a second position wherein said second rod occupies substantially the entire second conduit to isolate said open end thereof from said first conduit.

2. The device as defined in claim 1 including means for supplying a pressurized gas to said second conduit to blow said powder supplied to said second conduit from said first conduit out of said open end before said second rod is moved from its first to its second positions.

3. The device as defined in claim 2 wherein said first and second rods fit relatively tightly in their respective. conduits to advance powder along said conduits as said rods are reciprocated respectively from their first to their second positions. l i

4. The device as defined in claim 3 wherein said means for reciprocating said rods are sequentially operated, and said means for reciprocating said first rod moves said first rod from its first to its second position before said means for reciprocating said second rodmoves said second rod from its first to its second position.

5. The device as defined in claim 4 wherein said means for reciprocating said rods each comprise control cylinders.

6'. The device as defined in claim 5 including stuffing boxes associated with each of said conduits for forming a gas seal with said rods and vacuum means for drawing off gas leaking past said seals.

I l 1 i i 

1. A device for delivering a measured charge of a flowable powder, said device comprising a storage container for said powder and a buffer vessel located downstream of said storage container and in communication therewith through a flow passage in said device, means defining first and second flow conduits in said device with said first conduit being located in communication with said buffer vessel and in axial alignment with said flow passage, said second conduit being located at an angle with respect to said first conduit, in communication therewith, and having an open discharge end; a first elongated rod slidably mounted in said flow passage for reciprocating movement therein and having one end thereof slidably received in said first conduit, said first elongated rod having a constriction formed therein intermediate its ends, and means for reciprocating said first elongated rod between first and second positions wherein, at said first position said constriction is located in said storage container to receive said measured charge of powder and said one end of the rod is located in said buffer vessel, and at said second position said constriction is located in said buffer vessel to deposit said measured powder charge therein and said one end of the rod is located in said first conduit; a second elongated rod slidably received in said second conduit, and means for reciprocating said second rod independently of said first rod between a first retracted position wherein said second conduit is opened to provide communication between the open end thereof and said first conduit and a second position wherein said second rod occupies substantially the entire second conduit to isolate said open end thereof from said first conduit.
 2. The device as defined in claim 1 including means for supplying a pressurized gas to said second conduit to blow said powder supplied to said second conduit from said first conduit out of said open end before said second rod is moved from its first to its second positions.
 3. The device as defined in claim 2 wherein said first and second rods fit relatively tightly in their respective conduits to advance powder along said conduits as said rods are reciprocated respectively from their first to their second positions.
 4. The device as defined in claim 3 wherein said means for reciprocating said rods are sequentially operated, and said means for reciprocating said first rod moves said first rod from its first to its second position before said means for reciprocating said second rod moves said second rod from its first to its second position.
 5. The device as defined in claim 4 wherein said means for reciprocatinG said rods each comprise control cylinders.
 6. The device as defined in claim 5 including stuffing boxes associated with each of said conduits for forming a gas seal with said rods and vacuum means for drawing off gas leaking past said seals. 